Solve for $x$ and $y$ by deriving an expression for $x$ from the second equation, and substituting it back into the first equation. $\begin{align*}7x-4y &= 5 \\ 3x-3y &= -3\end{align*}$
Explanation: Begin by moving the $y$ -term in the second equation to the right side of the equation. $3x = 3y-3$ Divide both sides by $3$ to isolate $x$ $x = {y - 1}$ Substitute this expression for $x$ in the first equation. $7({y - 1}) - 4y = 5$ $7y - 7 - 4y = 5$ Simplify by combining terms, then solve for $y$ $3y - 7 = 5$ $3y = 12$ $y = 4$ Substitute $4$ for $y$ in the top equation. $7x-4( 4) = 5$ $7x-16 = 5$ $7x = 21$ $x = 3$ The solution is $\enspace x = 3, \enspace y = 4$.